The present invention relates to a two phase material using a high molecular weight polymer material as a matrix material and with fine particles dispersed therein as reinforcing material, and to a method of making such a two phase material.
The present patent application is based upon and claims the priority of Japanese patent application Ser. No. 127442/83 dated July 13, 1983; and hereby the material and subject matter of said Japanese patent application are incorporated into this specification by reference; a copy of said application is appended to this specification.
It has been recognized in the past that it is possible to supplement various deficiencies of a high weight polymer material without deteriorating its good characteristics by dispersing particles of metal or a metallic compound within the high weight polymer material. (In this connection, in this specification, the word "metal" will be used to include, not only conventional metals such as copper and aluminum, but also elements which have metallic properties in certain circumstances; in particular, to include silicon). Therefore, in the prior art, attempts have been made to give the characteristics of electroconductivity or electrosemiconductivity to high molecular weight polymer materials such as plastics, elastomers, and paints by melting them (i.e. heating them to a state in which their viscosity is very low) and then infusing into them metallic particles and dispersing these metallic particles. Also, attempts have been made to give the characteristics of good rigidity and dimensional stability to plastics by melting them and then infusing and dispersing into them particles of hard metal or ceramics such as alumina and silica. In the case of such a two-phase material including a high molecular weight polymer as a matrix material and dispersed particles of metal or metal compound, in order to effectively supplement the deficiencies of the polymer without deteriorating its useful properties the particles to be mixed must be minute and uniformly dispersed in said polymer material; and further, in order to make the resulting particle dispersion composite material economically, the mixed in particles must be economically available.
However, in the prior art such particle dispersion composite materials have been made by utilizing mixed particles with diameters in the range of from one micron to tens of microns, which have been formed by mechanical breaking methods, evaporation-in-gas methods, or atomization methods. Also, the method typically used for dispersing these mixing particles in the molten polymer matrix material has been either simply to mix them mechanically, or alternatively to utilize the so called jet dispersal method in which a jet of the particles mixed with argon gas is introduced into the molten matrix material. Since particles with an average diameter of less than one micron cannot be economically produced by such mechanical breaking methods and the like, and, since the particles as described above have small surface activity and have relatively poor wettability with the molten high molecular weight polymer matrix material, the problem arises that unevenness in the mixing particle distribution inevitably tends to occur between higher and lower strata of the molten composite material, due to the difference in specific gravities between the particles and the polymer matrix material. In other words, it is very difficult or impossible to evenly distribute such particles in the matrix material by mechanical mixing or by the jet dispersal method.